Methods for producing a conversion element and an optoelectronic  component

ABSTRACT

The invention relates to a method for producing a conversion element for an optoelectronic component comprising the steps of: A) Producing a first layer, for that purpose: A1) Providing a polysiloxane precursor material, which is liquid, A2) Mixing a phosphor to the polysiloxane precursor material, wherein the phosphor is suitable for conversion of radiation, A3) Curing the arrangement produced under step A2) to produce a first layer having a phosphor mixed in a cured polysiloxane material, which comprises a three-dimensional crosslinking network based primarily on T-units, where the ratio of T-units to all units is greater than 80%, B) Producing a phosphor-free second layer, for that purpose: B1) Providing the polysiloxane precursor material, which is liquid, B2) Mixing a filler to the polysiloxane precursor material, wherein the filler is in a cured and powdered form, wherein the filler has a refractive index, which is equal to the refractive index of the cured polysiloxane material, B3) Curing the arrangement produced under step B2) to produce a second layer having a filler mixed in the cured polysiloxane material, which comprises a three-dimensional crosslinking network based primarily on T-units, wherein the produced conversion element is formed as a plate having a thickness of at least 100 μm.

BACKGROUND OF THE INVENTION

The invention relates to methods for producing a conversion element foran optoelectronic component. The invention further relates to anoptoelectronic component, in particular a light-emitting diode.

There is a need in the industry for optoelectronic components for adown-conversion material that, when combined with the bluelight-emitting chip, generates a warm white spectrum with good colorrendering. This generally implies that at least two phosphorcompositions are required, for example a green garnet-type phosphor anda red nitride-type phosphor. Additionally, this down-conversion materialmust simultaneously tolerate both high blue light fluxes and hightemperatures over long periods of time. The standard ways of makingdown-conversion materials all have drawbacks when a warm white, high CR1solution is needed. For example, the familiar phosphor and siliconedown-converters, which are found in many products today, are notsufficient because the silicone materials degrade rapidly at high lightflux and temperatures. Single crystal and ceramic down-conversionmaterials can tolerate high light flux and temperatures because theyhave relatively high thermal stability and thermal conductivities, butthey are generally limited to one phosphor composition, which means thatthey cannot produce the required warm white spectrum. Thephosphor-in-glass and phosphor-on-glass down-conversion approaches aresuitable for accommodating multiple phosphor compositions but only ifthe processing temperature is kept below about 350° C. or the rednitride phosphors start to degrade. The phosphor-in-glass andphosphor-on-glass down-converters have better thermal stability than thephosphor and silicone down-converters but their thermal conductivitiesare inferior to the ceramic or single crystal alternatives. The downsideof the phosphor-in-glass or phosphor-on-glass approach is that the moststable glasses require processing temperatures above 350° C. There isstill a need for a material that can accommodate more than one phosphorcomposition, is stable at high temperatures and high light flux and canbe processed safely at under 350° C.

On surface-emitting, or thin-film type, optoelectronic components, likeLEDs, the top surface of the LED chips is where the major share of lightis emitted. For such LEDs it is common to place the down-convertingelement as close to the top surface as possible. One of the main reasonsfor this is thermal management. Stokes heat generated in thedown-conversion process can be effectively removed through the LEDdevice. Most thin-film type LEDs require at least one wire bond near thetop surface in order to supply electricity. These wire bonds protrudeabove the top of the chip. The distance above the chip surface dependson the design of a given product but is typically in the order of about125 μm. These wire bonds are fragile and cannot be exposed so that theyare typically encapsulated in a protective material. Forhigh-luminescence applications it is an often used practice to glue adown-converter directly on the chip surface. Then, to reduce emissionfrom the sides of the down-converter, the sides of the converters arecovered by a highly reflective material. The most common reflectivematerial is titanium dioxide powder dispersed in a silicone. Not onlydoes the titania-in-silicone prevent side emission, it also providesprotection for the bond wires. This places a limitation on the thicknessof the down-converter. It should be at least as tall as the distance bywhich the bond wire protrudes above the chip so that the side castingprocess completely covers the wire bond but does not block the forwardlight path.

Therefore, for uses in an LED package, the down-converter needs to beabout 125 μm thick or even thicker. This thickness limitation is notideal from a thermal management point of view. It is better if aconversion element is located in a more concentrated area near the chip.In this way, the Stokes heat can be removed from the phosphor throughthe LED chip. Therefore, there is a need for a conversion element thathas the conversion material concentrated in a small volume with athickness of less than 150 μm. The remainder of the 150 μm thickness cancome as an additional layer or additional layers that do not containdown-conversion material.

SUMMARY

The aim of the invention is to provide methods for producing aconversion element for an optoelectronic component. Each of the methodsproduces a conversion element that overcomes the above-mentioneddisadvantages. A further aim of the invention is to provide anoptoelectronic component comprising a conversion element which isproducible by the above-mentioned methods and overcomes theabove-mentioned disadvantages.

These objects are achieved by methods for producing a conversion elementfor an optoelectronic component according to independent claims 1 and16. Advantageous embodiments and developments of the invention are thesubject-matter of the dependent claims. Furthermore these objects aresolved by an optoelectronic component according to independent claim 13.Advantageous embodiments and developments of the optoelectroniccomponent are the subject-matter of dependent claims 14 and 15.

In at least one embodiment the method for producing a conversion elementfor an optoelectronic component comprises the following steps:

-   A) Producing a first layer, for that purpose:-   A1) Providing a polysiloxane precursor material, which is liquid,-   A2) Mixing a phosphor to the polysiloxane precursor material,    wherein the phosphor is suitable for conversion of radiation,-   A3) Curing the arrangement produced under step A2) to produce a    first layer having a phosphor mixed in a cured polysiloxane    material, which comprises a three-dimensional crosslinking network    based primarily on T-units,-   B) Producing a phosphor-free second layer, for that purpose:-   B1) Providing the polysiloxane precursor material, which is liquid,-   B2) Mixing a filler to the polysiloxane precursor material, wherein    the filler is in a cured and powdered form, wherein the filler has a    refractive index, which is equal to the refractive index of the    cured polysiloxane material or equal to the refractive index of the    precursor material e.g. a polysiloxane material,-   B3) Curing the arrangement produced under step B2) to produce a    second layer having a filler mixed in the cured polysiloxane    material, which comprises a three-dimensional crosslinking network    based primarily on T-units, wherein the produced conversion element    is formed as a plate having a thickness of at least 100 μm.

Here and in the following, based primarily on T-units can mean that theratio of T-units to all units, e.g. D-units, is greater than 80%.

Here and in the following, “the filler has an refractive index, which isequal to the refractive index of the cured polysiloxane material and/orequal to the refractive index of the precursor material” can mean thatthe refractive index of the filler is identical to the refractive indexof the cured polysiloxane material and/or precursor material withrespect to at least two positions behind the decimal point of therefractive index. For example, if the cured polysiloxane material has arefractive index of 1.43 then the filler has a refractive index of 1.43.

Here and in the following, the polysiloxane precursor materials asprovided in steps A2 and/or B2 can be different or the same. Forexample, the polysiloxane precursor materials of steps A2 and/or B2 candiffer in their organic content or alkoxy content. Alternatively, thepolysiloxane precursor materials of steps A2 and/or B2 can have anidentical composition.

Here and in the following, the cured polysiloxane materials in steps A3and/or B3 can be different or the same.

Here and in the following, the filler can be made of the same curedpolysiloxane material as mentioned in steps A3 and/or B3 or can be anyother filler with an equal refractive index than the polysiloxaneprecursor. The filler is in a powdered form compared to the curedpolysiloxane material mentioned in steps A3 and/or B3, which is mixed tothe cured polysiloxane material mentioned in step B3.

Here and in the following, steps A1 to A3 are substeps of step A,Producing a first layer. Steps B1 to B3 are substeps of step B,Producing a second layer. Step A with its substeps A1 to A3 can beperformed and subsequently Step B with its substeps B1 to B3 can beperformed. Alternatively, Step B with its substeps B1 to B3 can beperformed and subsequently Step A with its substeps A1 to A3 can beperformed. Alternatively, a part of substeps A1 to A3 and B1 to B3,respectively, can be performed simultaneously.

In particular, the filler is a polysiloxane material in a cured andpowdered form.

The invention further relates to an optoelectronic component.

In at least one embodiment the optoelectronic component comprises asemiconductor layer sequence. The semiconductor layer sequence is ableto emit radiation. In particular, the semiconductor layer sequence emitsradiation of the blue spectral range in operation. The optoelectroniccomponent comprises a conversion element. The conversion element ispreferably produced by a method according to claim 1. All stateddefinitions and embodiments of the method for producing a conversionelement are therefore also applicable to the optoelectronic componentand vice versa.

The conversion element is arranged directly on the surface of thesemiconductor layer sequence. In particular the surface of thesemiconductor layer sequence is the main surface, which means that thisis the surface of the semiconductor layer sequence where most of thelight is emitted. The conversion element comprises at least two layers,a first layer and a second layer. The first layer comprises a phosphor,which means at least one phosphor or a plurality of phosphors. One or aplurality of phosphors are mixed in a cured polysiloxane material oranother filler with an equal refractive index than the polysiloxaneprecursor material.

The second layer comprises a filler. The filler is mixed in a curedpolysiloxane material. The filler is the powdered and cured polysiloxanematerial or another filler with an equal refractive index than thepolysiloxane precursor material or the polysiloxane material. Inparticular, the filler is identical in its composition with the curedpolysiloxane material produced after step A3 or B3. The filler ispowdered compared to the cured polysiloxane material produced after stepA3 or B3.

In particular, the filler is the same material as the cured polysiloxanematerial mentioned in the second and/or first layer. The content of thefiller in the phosphor-containing first layer is equal to the content ofthe filler in the second layer. In particular, the content of totalfiller in the phosphor-containing first layer is equal to the volumecontent of the filler in the second layer. Here “content” means inparticular the volume percent with respect to the respective layers. Thecured polysiloxane material in the first and second layers eachcomprises a three-dimensional crosslinking network. Thethree-dimensional crosslinking network is primarily based on T-units.

The inventors have found out that the methods for producing a conversionelement as described herein produce a conversion element which has a lotof positive properties. The conversion element is formed as a platehaving a thickness of at least 100 μm or 125 μm. In particular thethickness of the conversion element is in the range of 100 μm to 200 μm.The conversion element comprises at least two phosphors which areblended and result in a warm-white color temperature with a CRI of equalto or more than 90 (CCT<4100 K). Alternatively, a blend of at least twophosphors can be selected to result in a cool-white color temperaturewith a CRI of equal to or more than 90 (CCT≥4100 K).

The conversion element has a long-term stability under high incidentblue light flux (≥1.5 A/mm²). The conversion element has a long-termtemperature stability (T>150° C.). The conversion element has along-term stability against moisture.

Ceramic, single crystal and thin-film (e.g. PLD-grown) phosphors cannotproduce the required spectrum from a single bound conversion element.Phosphor and silicone down-converters are not stable under the high heatand flux conditions. Phosphor-in-glass and phosphor-on-glass are thebest alternatives in that the glass or glass-like phosphor matrix mustbe processable at temperatures below 350° C. and must be stable againstmoisture and demanding conditions. This is the challenge for known glassmaterials as produced according to this invention.

This invention makes it possible to prepare a photothermally stabledown-conversion element or a conversion element, comprised of one ormore inorganic phosphor materials dispersed in a highly crosslinkedpolysiloxane matrix or crosslinked polysiloxane matrix material arrangedin a layered configuration such that the phosphor material is alllocated in close proximity to the chip or to the main surface of thesemiconductor layer sequence.

The key advantages of this invention are:

-   -   the conversion element is thermally more stable than an analogue        material based on a standard optical silicone matrix. This is        due to the relatively low amount of organic material in the        polysiloxane material compared to standard optical silicones.        The thermogravimetric analysis plot shows how much organic        material is present in one of the best low refractive index        optical silicones used today in high-power applications compared        to the disclosed polysiloxane material (see FIG. 2). The fully        cured polysiloxane only has preferably about 15 wt % organic        content, whereas the silicone reference has about 60 wt %        organic content.    -   The highly crosslinked polysiloxane-based converter element can        be made with cleaner or sharper edges than a screen-printed        silicone-based converter. This is important for the        titania-in-silicone side-cast reflector.    -   The down-conversion element can be made using an inexpensive        process at room temperature.    -   Because the fabrication process does not require high        temperatures or solvents, the conversion element is compatible        with nearly all phosphors, so that different colors, from blue        to red, including combinations, for example cool and warm-white        blends, are possible. This is a key distinguishing feature from        ceramic converters, where blends, for example warm white, are        currently not possible.    -   Unlike the current phosphor-in-glass or phosphor-on-glass and        nitride-based ceramic approaches, which rely on dicing to        singulate the individual conversion elements, this technology is        compatible with tape-casting and punching, which simplifies the        manufacturing steps and reduces costs.    -   Unlike the current silicone-based down-conversion elements that        are made with screen-printing or tape casted foils applied by        vacuum forming lamination, this method produces parts that are        more uniform in terms of brightness and color point because        their thickness and surface roughness are better controlled.    -   Because the polysiloxane precursor material is a liquid, it is        possible to incorporate different additives into the converter        element such as nanoparticles, metal alkoxy precursors, organic        molecules, polymers, etc. If additives are desired, they can        serve different purposes, such as controlling the viscosity        during fabrication, providing crack resistance and enhanced        mechanical strength, tuning the refractive index, increasing        thermal conductivity, etc.    -   A particular class of alkoxy methyl siloxane precursors lends        itself to be used with or without a solvent. Some preferred        embodiments use the solvent-free approach, which is a        distinguishing factor from other materials that require solvent        for one reason or another, for example to decrease viscosity to        make them more processable, to dissolve solid materials to make        them solution-proccesable, etc.    -   In one preferred embodiment, the phosphor-filled first layer and        the phosphor-free second layer contain the same polysiloxane        material or the same cured polysiloxane material. This results        in strong chemical bonds being formed between the two layers,        which means between the first and second layers, which is not        necessarily the case if the phosphor-free layer were made of a        different material.

According to one embodiment the polysiloxane precursor material in thefirst and/or second layer comprises the formula:

wherein T1 and T2 represent terminal groups, R1 to R4 each representside groups, 0.8≤n≤1, 0≤m<0.2 and n+m=1.

According to one embodiment the content of the phosphor in the firstlayer is equal or almost equal or similar to the content of the fillerin the second layer. “Almost equal” or “similar” can mean that thevolume content of the total filler in the phosphor-containing firstlayer differs from the content of the filler in the second layer by amaximum of 10%, 5%, 4%, 3%, 2%, 1% or 0.5%.

According to one embodiment the second layer is directly applied on thefirst layer, wherein the first and second layers are arranged on asurface of a semiconductor layer sequence of the optoelectroniccomponent, wherein the conversion element at least partially absorbs theradiation of the semiconductor layer sequence of the optoelectroniccomponent and comprises at least two layers.

The optoelectronic component comprises at least one optoelectronicsemiconductor chip. The optoelectronic semiconductor chip can have thesemiconductor layer sequence. The semiconductor layer sequence of thesemiconductor chip is preferably based on a III-V compound semiconductormaterial. For example, this includes compounds from the elementsconsisting of indium, gallium, aluminium, nitrogen, phosphorus, arsenic,oxygen, silicon, carbon and combinations thereof. However, otherelements and additions can also be used. The semiconductor layersequence having an active region can be based, for example, on nitridecompound semiconductor materials. In the present context, “based onnitride compound semiconductor material” means characterized in that thesemiconductor layer sequence or at least a part thereof is a nitridecompound semiconductor material, preferably Al_(n)Ga_(m)In_(1-n-m)N, orconsists thereof, wherein 0≤n≥1, 0≥m≥1 and n+m≤1. This material does notnecessarily have a mathematically exact composition according to theabove formula. Rather, it can have, for example, one or more dopants andadditional constituents. For the sake of simplicity, however, the aboveformula only contains the essential constituents of the crystal lattice(Al, Ga, In, N), even if these can be partially replaced and/orsupplemented by small quantities of further substances.

The semiconductor layer sequence comprises an active layer having atleast one pn-junction and/or having one or more quantum well structures.During operation of the LED or of the semiconductor chip, anelectromagnetic radiation is generated in the active layer. A wavelengthor a wavelength maximum of the radiation is preferably in theultraviolet and/or visible and/or infrared spectral range, in particularat wavelengths between 420 and 800 nm inclusive, for example between 440and 480 nm inclusive.

According to one embodiment the first layer has a thickness of 20 μm to80 μm, in particular between 40 μm and 60 μm, for example 55 μm.

According to one embodiment the polysiloxane precursor material is amethyl methoxy polysiloxane having an methoxy content ranging from 10 wt% to 50 wt %.

According to one embodiment the polysiloxane precursor material is amethyl alkoxy polysiloxane having an alkoxy content ranging from 10 wt %to 50 wt %.

According to one embodiment the first and the second layers are appliedby means of spray-coating, dip-coating, spin-coating, drop-casting,tape-casting or doctor blading.

According to one embodiment, the first and/or second layers are producedby tape-casting.

According to one embodiment the polysiloxane precursor material has amolecular weight of less than 5000 g/mol, preferably less than 1500g/mol, preferably less than 1400 g/mol, 1300 g/mol, 1200 g/mol, 1100g/mol 1000 g/mol or 900 g/mol.

According to one embodiment the first and/or second layers comprisefumed silica for increasing their viscosity.

According to one embodiment, the first and/or second layer comprise(s)fumed silica, wherein the content of the fumed silica is in the range of5 wt % to 40 wt %, preferably between 20 wt % and 33 wt %, with respectto the cured polysiloxane material.

According to one embodiment the first and/or second layers arecrosslinked to each other at their interface.

According to one embodiment the first and/or second layers arechemically crosslinked to each other at their interface forming a singlecrosslinked network.

According to one embodiment the method for producing a conversionelement comprises a polysiloxane precursor material. The polysiloxaneprecursor material can be provided in steps A1 and/or B1. This precursormaterial can be different in each of the steps or can be the samematerial. The polysiloxane precursor material belongs to a particularclass of siloxanes.

In particular, the precursor or polysiloxane precursor material is a lowmolecular weight alkoxy polysiloxane where the alkoxy content is in theorder of about 35 wt %.

The polysiloxane precursor material is liquid. In particular, thepolysiloxane precursor material is liquid at room temperature.

An ideal example structure of such a precursor material is shown asfollows:

The number of repeat units n can vary and should be chosen so that theviscosity of the precursor is in the order of 1 to 80 mPas. The numberof repeat units n can be: n=2-20.

When exposed to water, and typically a catalyst, the polysiloxaneprecursor material of step A1 and/or B1 undergoes hydrolysis andcondensation reactions which crosslink the low molecular weightpolysiloxane units into a dense polysiloxane network. In particular thecured polysiloxane material made from the polysiloxane precursormaterial comprises a three-dimensional crosslinking network primarilybased on T-units. Additionally D-units can be present to increase theflexibility of the cured material. The ratio of T-units to all units,e.g. D-units, can be greater than 80%. The content of D-units to allunits can be at most 20%.

In general polysiloxanes have different structural units, for example Q,T, D or M units. Each of them has different functions. M units terminatechange or three-dimensional entities. A higher proportion of M unitstherefore results in a lower molecular mass of the silicone. Thecombination of D-units results in chains, while each of the Q-unit andT-unit is a branching point. A person skilled in the art knows what ismeant by T-unit. A T-unit can mean here and in the following that onesilicone atom has three bonds to three oxygen atoms. A D-unit can meanhere and in the following that one silicone atom has two bonds to twooxygen atoms.

In reality not all of the methoxy groups necessarily result incrosslinking. Some of them can remain intact and some of them can bereplaced by the silanol groups.

The following formula shows an example structure of a highly crosslinkedcured polysiloxane material that can result from the hydrolysis andcondensation of the polysiloxane precursor material. It should be notedthat the structure is a schematic example that is easy to visualize butis not meant to be technically accurate.

According to one embodiment fumed silica is added to the polysiloxaneprecursor material. The fumed silica increases the viscosity, reducesshrinkage during curing and makes a slurry for a down-conversion layer.Once the fumed silica is roughly incorporated, the desired phosphorpowder or blend of the phosphor powders are dispersed in the liquidpolysiloxane precursor material as well.

If desired, other additives, for example nanoparticles, can also beadded to the liquid polysiloxane precursor material.

Typically a catalyst, for example a titanium alkoxide, is added in therange of 1 wt % to 5 wt % of the polysiloxane material, curedpolysiloxane material or polysiloxane resin. The relative amounts ofphosphor and additives depend on many criteria, such as the size of theparticles, the desired color point, the volume and thickness of theconversion layer, the wavelength of exciting radiation, the type ofpump, for example laser or LED, the amounts of other additive materialsand other considerations.

According to one embodiment the fumed silica can also be added to thesecond layer, which is the phosphor-free layer, to make the slurry forthe phosphor-free layer. The fumed silica increases the viscosity.

If desired, other additives can also be added to the liquid polysiloxaneprecursor material which is provided in step B1. Typically a catalystsuch as a titanium alkoxide is added in the range of 1 wt % to 5 wt % ofthe cured polysiloxane material or polysiloxane resin. The relativeamount of the fumed silica, catalyst or perhaps other additives dependson many criteria such as the desired viscosity, the desired transparencyand the desired thickness, among others.

According to one embodiment the converter element is formed as amultilayer structure. The phosphor-containing slurry can be dispensed byany of a number of techniques such as spray-coating, dip-coating,spin-coating, drop-casting, tape-casting or doctor blading. It can bedispensed on a permanent substrate, a temporary substrate or on the LEDitself.

In one embodiment the first layer is only partially cured in step A3,and the phosphor-free second layer can be dispensed over the top by anyof the methods listed above. In the presence of humidity or if liquidwater was added to the precursor solution, the mixture will begin tocure at room temperature. If desired, curing can be accelerated byapplying increased temperature. The two layers of the conversion elementcan form onto one material held tightly together by a highly crosslinkedpolysiloxane network. Even so, there is only one polysiloxane networkwith that the conversion element can retain its layer structure with thephosphor particles all being located near each other in one portion ofthe material.

According to one embodiment, the conversion element produced by a methodas claimed in claim 1 can be punched or diced to the proper shape andsize and incorporated into the optoelectronic component, for example alight-emitting diode package or laser-activated module.

According to one embodiment the polysiloxane precursor material asprovided in step Al or BI is a methyl methoxy polysiloxane. The methoxycontent can be in the order of 10 to 50 wt %, preferably in the range of15 to 45 wt %, even more preferably in the range of 25 to 40 wt %. Themolecular weight of the polysiloxane precursor material can be such thatthe viscosity is in the range of 1 to 80 mPas, but preferably in therange of 2 to 40 mPas.

For a lighting application that requires high CRI (>90) the conversionelement can comprise at least two phosphors. The phosphor mixture can bea blend of cerium-activated lutetium aluminum garnet(Lu_(1-x)Ce.)₃Al₅O₁₂ wherein 0<x≤0.2 and the europium-activated calciumaluminum silicone nitride,

(Ca_(1-x)Eu_(x))AlSiN₃ where 0<x≤0.2. The concentration and ratio of thephosphors depends on the cerium and europium concentrations of phosphorsabsorptances and quantum efficiency, the target thickness, the targetcolor point and whether there are other scattering additives present.The ratio of garnet to nitride phosphor can be within the range of 2.1:1to 4.5:1.

According to one embodiment at least two phosphors, fumed silica and thepolysiloxane precursor material, are added to form a first layer. Thecontent of the fumed silica is preferably in the range of 5 to 35 wt %.The content of the two phosphors is in the range of 20 to 80 wt %. Thecontent of the polysiloxane precursor material is in the range of 10 to

75 wt %. After being thoroughly mixed, 1 to 5 wt % (of the polysiloxaneresin or cured polysiloxane material or polysiloxane) tetra-n-butyltitanate is added as a catalyst. A separate phosphor-free second layermixture can be produced in parallel with the same polysiloxane precursormaterial, for example in the range of 65 to 95 wt %, fumed silica, forexample in the range of 5 to 35 wt %, and tetra-n-butyl titanatecatalyst.

The phosphor-containing precursor mixture for forming the first layercan then be tape-casted on, for example, a non-stick polymer sheet suchas silicone-coated Mylar. Mylar is a trade name of DuPont for apolyethylene terephthalate polyester film (BOPET: biaxially orientedpolyethylene terephthalate). The target thickness of this layer in thefinal cured state of the first layer can be in the order of 10 μm to 100μm, but preferably between 25 μm and 75 μm. Before this first layer hasbeen completely cured the phosphor-free precursor mixture can betape-casted over the first layer. The overall thickness of both layersin the final cured state of the conversion element can be in the orderof 100 to 250 μm, but more preferably between 120 and 250 μm. Thetwo-layer tape is then allowed to cure at room temperature in ordinaryambient conditions. The curing time depends on the thickness of thetape, the amount of catalyst and the relative humidity. Typically thematerial forms a skin within an hour but requires a longer time for thefull.

According to one embodiment, once cured the multi-layer conversionelements are punched out of the tape using, for example, a numericalcontrol (NC) punch tool. Once punched, the individual platelets areready to be incorporated into an optoelectronic component, for exampleinto a light device based on a light-emitting diode, LED, or a laserdiode (LD).

According to one embodiment the cured polysiloxane material is a highlycrosslinked network primarily made of siloxane bonds. The siloxanenetwork is formed from a liquid or solution-based siloxane precursor.The generic formula for the reactive polysiloxane precursor is shownbelow:

wherein T1 and T2 represent terminal groups, R1 to R4 each representside groups, 0.8≤n≤1, 0≤m<0.2 and n+m−1.

In some embodiments the R- and T-groups can all be the same, for examplea methyl group. In other embodiments each functional group can be adifferent group. In another embodiment some of the groups can be thesame and some can be different. In some cases one of the groups can bemade up of more than one functional group. For example, one embodimentcan involve a precursor material where m=0, R¹=methyl, and R² is acombination of methyl and phenyl.

According to one embodiment the polysiloxane precursor material can be amethyl methoxy polysiloxane where the methoxy content ranges from 10 wt% to 50 wt %, but is preferably closer to 15 wt % to 45 wt %, even morepreferably to 25 wt % to 40 wt %. The structure can be like what isshown above, but it can also be another combination of a polysiloxanebackbone with metyl and methoxy side groups.

For example there can be silicone atoms with two methyl groups or twomethoxy groups as long as the total methoxy content falls within theranges above. The number of siloxane monomer units in the polysiloxaneprecursor material can be such that the viscosity is in the order of 1to 150 mPas but preferably in the range of 1 to 60 mPas and even morepreferably in the range of 2 to 40 mPas. The polysiloxane precursormaterial, also called precursor, can also be partially reacted like thefollowing example, but non-limiting, formula:

In a partially reacted precursor the methoxy content can be lower thanin the pristine, unreacted precursor and viscosity can tend to behigher.

According to one embodiment the terminal groups of the polysiloxaneprecursor material can contain one or more chemical reactive groups suchas alkoxy, vinyl, hydroxyl, carboxylic acid, ester, or any other of thereactive functional groups know from the organic chemistry field.

According to another embodiment the terminal groups can be less reactivesuch as hydrogen, methyl, ethyl or any alkyl or aryl groups.

According to one embodiment methyl and methoxy side groups arepreferred. This does not exclude other functional groups such as ethyl,ethoxy, phenyl, phenoxy, vinyl, trifluoropropyl.

According to one embodiment m=0, R² is either a methyl, a phenyl or acombination of the two, and R¹=ethyl with an ethoxy content of 10 to 50wt %, but more preferably 20 to 30 wt %, and/or a viscosity in the rangeof 30 to 70 mPas. A small amount of solvent can be present in thisembodiment.

According to an embodiment m=0, R² is a combination of methyl andphenyl, and R¹ is a methyl group. The methoxy content is 10 to 20 wt %along with a viscosity of 100 to 50 mPas.

The precursor or the polysiloxane precurs& material can instead be basedon a polysilazane precursor, which has a chemical backbone ofalternating silicone and nitrogen atoms. The side groups can be hydrogenor any of those listed above. In the presence of water, the polysilizanecan react to form a dense polysiloxane network similar to that formedfrom the siloxane-based precursors.

According to one embodiment the optoelectronic component or the firstlayer of the optoelectronic component comprises at least two differentphosphors. The first phosphor is able to emit red radiation. The secondphosphor is able to emit green radiation. In particular theoptoelectronic component emits warm white light in operation.

According to one embodiment of the optoelectronic component the firstlayer comprises two sublayers. The two sublayers are stacked one on topof the other. The first sublayer of the two sublayers is arrangeddirectly on the surface of the semiconductor layer sequence andcomprises the phosphor emitting red radiation in operation. The secondsublayer is arranged directly on the first sublayer and comprises afurther phosphor emitting green radiation in operation.

According to one embodiment the conversion element comprises two layerswherein the same cured polysiloxane material is used in both layers andthe crosslinked siloxane network is continuous from one layer to theother. The layering is achieved by having all of the phosphor particlesin a densely packed area. In this embodiment the phosphor-free secondlayer can also be transparent. The total thickness can be greater than150 μm and the phosphor-containing second layer can account for >50% ofthe total thickness.

According to an embodiment the phosphor-free second layer can be made toact as a diffusor by adding some scattering particles. Scatteringparticles can be, for example, aluminum oxide, titanium dioxide orsilicone dioxide.

According to one embodiment the conversion element comprises threelayers. The three layers comprise the same cured polysiloxane materialin all layers. The three layers are crosslinked and form a crosslinkedsiloxane network. The crosslinked siloxane network is continuous fromone layer to the next. The total thickness can be greater than 120 μm.This multilayer design can be any configuration of the three layers.

According to one embodiment the conversion element comprises more thanthree, for example four and more, layers. These layers can bedifferently combined with different phosphor layers, clear layers anddiffusive layers.

The cured polysiloxane material does not need to have the samecomposition from layer to layer. For example, the cured polysiloxanematerial in the phosphor-containing layer can be one that containsphenyl groups for the purpose of having a higher refractive index forbetter light out-coupling. The clear layer (layer without a phosphor)can be based on a polysiloxane with a lower refractive index, which canprovide an index step that is closer to air, which can also help withlight extraction.

According to one embodiment the phosphor-containing first layer is stillbased on a polysiloxane material, while the phosphor-free second layersare not necessarily made from polysiloxanes. For example thephosphor-layers comprises glass, quartz, sapphire, patterned sapphire,traditional optical silicones, etc.

According to one embodiment the top surface of the multilayer conversionelement can be structured for light extraction. The top surface can beflat but it can also be structured by incorporating random roughness,microlenses or other micro-optics, photonic crystals, plasmonic arrays,meta lenses, aperiodic nanostructured arrays, dielectric films or stacksof dielectric films, for example anti-reflective coatings, dichroicfilters, wavelength/angle-dependent pass filters, graded indexanti-reflective coatings. These surface modifications can be implementedor imparted by starting with a structured/patterned substrate andcasting the top layer first, or by post-processing steps.

According to another embodiment any or all of the layers are gluedtogether with an adhesive.

According to one embodiment the at least one phosphor can be selectedfrom the group consisting of:

-   (RE_(1-x)Ce_(x))₃(Al_(1-y)A′_(y))₅0₁₂ with 0<x≤0.1 and 0≤y≤1,-   (RE_(1-x)Ce_(x))₃ (Al_(5-2y)Mg_(y)Si_(y))O₁₂ with 0<x≤0.1 and 0≤y≤2,-   (RE_(1-x)Ce_(x))₃Al_(5-y)Si_(y)O_(12-y)N_(y) with 0<x≤0.1 and    0≤y≤0.5,-   (RE_(1-x)Cex)₂CaMg₂Si₃0₁₂:Ce³⁺ with 0<x≤0.1,-   (AE_(1-x)Eu_(x))₂Si₅N₈ with 0<x≤0.1,-   (AE_(1-x)Eu_(x))AlSiN₃ with 0<x≤0.1,-   (AE_(1-x)Eu_(x))₂Al₂Si₂N₆ with 0<x≤0.1,-   (Sr_(1-x)Eu_(x))LiAl₃N₄ with 0<x≤0.1,-   (AE_(1-x)Eu_(x))₃Ga₃N₅ with 0<x≤0.1,-   (AE_(1-x)Eu_(x))Si₂O₂N₂ with 0<x≤0.1,-   (AE_(x)Eu_(y))Si_(12-2x-3y)Al_(2x+3y)O_(y)N_(16-y) with 0.2≤x≤2.2    and 0<y≤0.1,-   (AE_(1-x)Eu_(x))₂Si0₄ with 0<x≤0.1,-   (AE_(1-x)Eu_(x))₃Si₂0₅ with 0<x≤0.1,-   K₂(Si_(1-x-y)Ti_(y)Mn_(x))F₆ with 0<x≤0.2 and 0<y≤1-x,-   (AE_(1-x)EU_(x))₅(PO₄)₃Cl with 0<x≤0.2,-   (AE_(1-x)Eu_(x))Al₁₀O₁₇ with 0<x≤0.2 and combinations thereof,    wherein RE is one or more of Y, Lu, Tb and Gd; AE is one or more of    Mg, Ca, Sr, Ba; A′ is one or more of Sc and Ga; wherein the    phosphors optionally include one or more of halides.

According to one embodiment the conversion element can comprisenanoparticles. The nanoparticles can be added to any of the layers inthe multilayer converter element to change properties such as therefractive index or thermal conductivities. The nanoparticles can beoxides, for example SiO₂, ZrO₂, TiO₂, Al₂O₃, ZnO; nitrides, for exampleAlN, Si₃N₄, BN, GaN; carbon-based nanoparticles, for example carbonnanotubes, graphene and their derivatives; heteropolyacids, for example12-tungstophosphoric acid (H₃PW₁₂O₄₀) or 12-tungstosilicic acid(H₄SiW₁₂O₄₀).

In some cases, to make them compatible, the surfaces of the inorganicnanoparticles are modified with capping agents to make them misciblewith the precursor compounds. The nanoparticles can be metal-organiccompounds such as alkoxides of silicone, zirconium, titanium, aluminum,and/or halfnium; organic molecules, for example adhesion promoters,plasticizers, de-foamers, thickeners, thinners or polymers, for exampleorganic (carbon based chain) or inorganic (non-carbon based chain). Somenon-exclusive examples can be poly(dimethyl siloxane), poly(methylphenylsiloxane), poly(diphenyl siloxane), poly(silphenylcne-siloxane),polyphosphazenes, polysilazane, perhydropolysilazane.

According to one embodiment the optoelectronic component is an organicor inorganic light-emitting device. In particular the optoelectroniccomponent is an inorganic light-emitting device, LED. The LED can be ofthe chip-on-board type or of the package LED type. The converter elementcan be deposited directly on the LED, it can be glued in close proximityto the LED or it can be in a remote configuration. The optoelectroniccomponent can also be a laser diode.

The invention further relates to a method for producing a conversionelement for an optoelectronic component comprising the steps of:

-   A) Providing a first carrier, selected from glass, sapphire, or    patterned sapphire,-   B) Applying a first connecting layer on the first carrier, wherein    the first connecting layer comprises a silicone or is produced by a    polysiloxane precursor material comprising the formula:

wherein T1 and T2 represent terminal groups, R1 to R4 each representside groups, 0.8≤n≤1, 0≤m<0.2 and n+m=1, and

-   C) Applying a conversion element on the first connecting element,    e.g. by means of tape casting,    wherein the conversion element is formed as a foil and comprises a    phosphor mixed in a cured polysiloxane material, which is produced    by a polysiloxane precursor material comprising the formula:

wherein T1 and T2 represent terminal groups, R1 to R4 each representside groups, 0.8≤n≤1, 0≤m<0.2 and n+m=1.

Additionally and/or optionally, the method can comprise a step D):

-   D) Applying a second connecting layer on the conversion element,    wherein the second connecting layer comprises a silicone or is    produced by a polysiloxane precursor material comprising the    formula:

wherein T1 and T2 represent terminal groups, R1 to R4 each representside groups, 0.8≤n≤1, 0≤m<0.2 and n+m=1.

Additionally and/or optionally, the method can comprise a step E) afterstep D):

-   E) Applying a second carrier on the second connecting element,    wherein the first and/or second carricr comprise(s) sapphire, glass    or a patterned sapphire substrate.

This patent application refers to the PCT application WO 2017/182390 A1,whose disclosure content of the polysiloxane precursor material and thecured polysiloxane material is hereby incorporated by reference.

Further advantageous embodiments and developments will become apparentfrom the exemplary embodiments described below in conjunction with thefigures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1I show a schematic illustration of a method for producing aconversion element for an optoelectronic component according to anembodiment;

FIG. 2 shows a thermogravimetric analysis profile according to oneembodiment and exemplary embodiments;

FIGS. 3A to 3D each show a schematic illustration of an optoelectroniccomponent according to an embodiment;

FIGS. 4A to 4E each show a microscopic image of an optoelectroniccomponent according to an embodiment;

FIG. 5 shows a schematic illustration of an optoelectronic componentaccording to an embodiment,

FIG. 6 shows the transmission of polysiloxane, methyl silicone andphenyl silicone; and

FIGS. 7A to 7E show the method for producing a conversion element for anoptoelectronic component according to one embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the exemplary embodiments and figures identical or identically actingelements can in each case be provided with the same reference symbols.The elements illustrated and their size relationships to one another arenot to be regarded as true to scale. Rather, individual elements suchas, for example, layers, components, devices and regions, can berepresented with an exaggerated size for better representability and/orfor a better understanding.

FIG. 1 shows a method for producing a conversion element for anoptoelectronic component. According to FIG. 1A a polysiloxane precursormaterial 12 for producing a first layer 1 is provided. The polysiloxaneprecursor material 12 is liquid and is provided in a reservoir or tank6. Then, the at least one phosphor or plurality of phosphors 11 is/aremixed to the polysiloxane precursor material 12 as shown in FIG. 1B.Then this mixture is tape-casted as shown in FIG. 1C and cured toproduce a first layer 1 having a phosphor or at least one phosphor 11mixed in a cured polysiloxane material 13, which comprises athree-dimensional crosslinking network primarily based on T-units.

According to FIG. 1D a polysiloxane precursor material 22 is provided ina tank 8. The polysiloxane precursor material 22 can be the same as thepolysiloxane precursor material 12 or different from the latter. Afiller 21 is mixed to the polysiloxane precursor material 22 in step B2(see FIG. 1E). This arrangement produced under step B2 is cured toproduce a second layer 2. The second layer 2 has a filler 21 which ismixed in the cured polysiloxane material 22. The cured polysiloxanematerial 22 comprises the three-dimensional crosslinking network withthe T-unit. As shown in FIG. 1F, the second layer 2 is directly appliedon the first layer 1. As shown in FIG. 1G, the produced conversionelement 10 can be diced 9. The conversion element 10 is, in particular,formed as a plate and has a thickness of at least 100 μm or 125 μm.

FIG. 1H shows a side view of an optoelectronic component 100 having ahousing 31. The housing 31 comprises a recess 32 in which an LED chip 3or semiconductor layer sequence 3 is arranged. On the semiconductorlayer sequence 3 the conversion element 10 is directly applied. Theconversion element 10 can be placed on the surface of the semiconductorlayer sequence 3 by the so-called pick-and-place process.

FIG. 1I shows a schematic side view of an optoelectronic component 100according to an embodiment. The optoelectronic component 100 comprises acarrier 33, a semiconductor layer sequence 3, a conversion element 10, abonding wire and bonding pad 34. The semiconductor layer sequence 3emits radiation in the direction of reference number 35. The conversionelement 10 covers the bonding wire 34 completely in the direction of theradiation direction 35 of the semiconductor layer sequence. Thisradiation direction 35 is also called the main radiation direction,which means in particular the direction of the radiation where the majorshare of the light is emitted.

FIG. 2 shows a thermogravimetric analysis profile of a methyl-basedsilicone reference 1 and a cured polysiloxane material 2 (methyl-basedpolysiloxane). The standard silicone 1 loses almost 60% of its weight,indicating a large organic content. The polysiloxane material 2 losesless than 20% of its weight, indicating a significantly lower organiccontent. The thermogravimetric analysis shows how much organic materialis present in one of the best low-refractive-index optical siliconesused today in high-power applications compared to the disclosedpolysiloxane material. The fully cured polysiloxane only has about 15 wt% organic content, whereas the silicone reference has about 60 wt %organic content.

FIGS. 3A to 3D show the schematic example of multi-layered conversionelements according to one embodiment.

As shown in FIG. 3A the optoelectronic component 100 shows a first layer1 comprising two sublayers 4 and 5. The first sublayer 4 comprises, forexample, a phosphor emitting red radiation and the second sublayercomprises a further phosphor emitting green radiation or vice versa. Thefirst sublayer 4 is directly arranged on the second sublayer 5. Abovethe second sublayer 5 a second layer, which is phosphor-free or alsocalled a clear layer, is arranged.

According to FIG. 3B the first and second sublayers 4, 5 areinterchanged compared to the optoelectronic component 100 according toFIG. 3A.

The optoelectronic component 100 according to FIG. 3C comprises a firstlayer 1. The first layer 1 comprises two different kinds of phosphors,for example a red-emitting and a green-emitting phosphor. The phosphorsare mixed and dispersed in the cured polysiloxane material. Theoptoelectronic component 100 comprises a second layer 2 which isarranged on the first layer 1. A diffusive layer 45 is arranged on thesecond layer 2. The diffusive layer 45 can comprise, for example,scattering particles like titanium dioxide.

The optoelectronic component 100 according to FIG. 3D shows a firstlayer 1 in which two different phosphors are mixed. Above the firstlayer 1 a diffusive layer 45 is arranged. Above the diffusive layer 45 asecond layer, which is phosphor-free, is arranged. In other words, thediffusive layer 45 is arranged between the first and the second layer 1,2.

FIGS. 4A to 4E each show microscopic images of optoelectronic componentsaccording to one embodiment. The images show the first and second layersand the total thicknesses d of 96 μm (FIG. 4A), of 112 μm (FIG. 4B) andof 178 μm (FIG. 4C).

In particular the images of FIGS. 4D and 4E each show the filler in thephosphor-free second layer 2. The filler is cured and in powdered form.In particular the content of the filler is equal to the content of thephosphor in the first layer. Equal means that the content is identicalwith a maximum tolerance of 0, 1, 3, 4 or 5 percent of this value. FIG.4E shows that the thickness of the first layer 1, e.g. 50 μm, is smallerthan the thickness of the second layer 2, e.g. 75 μm.

FIG. 5 shows a schematic illustration of an optoelectronic component 100according to an embodiment. The optoelectronic component 100 comprises asemiconductor layer sequence 3. A conversion element 10 is arranged onthe semiconductor layer sequence 3. The conversion element 10 comprisesa first layer 1 and a second layer 2. The first layer 1 comprises thecured polysiloxane 13 and the phosphor 11. The second layer 2 comprisesthe cured polysiloxane 23 and the filler 21. The first layer 1 has athickness d1. The second layer 2 has a thickness d2. The sum of thethicknesses d1 and d2 is the total thickness d of the conversion element10.

FIG. 6 shows the FTIR spectrum of polysiloxane 1, typical methylsilicone 2 and typical phenyl silicone 3. The transmission in percent isshown as the function of the wavelength in 1/cm. There is a distinctdifference between the position of the Si—O-vibration in the IR-spectrumof M, D, and T Q-units; FIG. 6 shows the Si—O-vibration of D-units(silicone, references 2 and 3) and T-units (polysiloxane, reference 1).The difference between T-units and D-units can be determined via FTIR.

FIGS. 7A to 7E show the method for producing a conversion element or anoptoelectronic component according to one embodiment. As shown in FIG.7A a first carrier 41 is provided. The first carrier 41 can comprisesapphire, glass or a patterned sapphire substrate (PSS).

On the first carrier 41 the first connecting layer 42 is applied,wherein the first connecting layer 42 comprises a silicone or isproduced by a polysiloxane precursor material as mentioned above. Then aconversion element 10 is applied on the first connecting element 42 bymeans of tape-casting. The conversion element 10 is preferably formed asa foil and comprises a phosphor or at least one phosphor mixed in acured polysiloxane material. The cured polysiloxane material is producedby a polysiloxane precursor material as mentioned above.

Optionally, a second connecting element 43 is applied on the conversionelement 10. The second connecting layer 43 comprises a silicone or isproduced by a polysiloxane precursor material as mentioned above. Thenthe second connecting element 43 can be applied on a surface of asemiconductor layer sequence.

Optionally and alternatively, a second carrier 44 can be applied on thesecond connecting element 43. The second carrier 44 can comprisesapphire, glass or a patterned sapphire substrate (PSS).

The exemplary embodiments described in conjunction with the figures andthe features thereof can also be combined with one another in accordancewith further exemplary embodiments, even if such combinations are notexplicitly shown in the figures. Furthermore, the exemplary embodimentsdescribed in conjunction with the figures can have additional oralternative features according to the description in the general part.

The invention is not restricted to the exemplary embodiments by thedescription on the basis of the exemplary embodiments. Rather, theinvention comprises any new feature and any novel combination offeatures, which includes in particular any combination of features inthe patent claims, even if this feature or this combination itself isnot explicitly specified in the patent claims or exemplary embodiments,

LIST OF REFERENCE NUMERALS

-   1 first layer-   2 second layer-   3 semiconductor layer sequence-   4 first sublayer-   5 second sublayer-   6 tank or reservoir-   7 silicone pad foil-   8 tank-   9 dicing-   10 conversion element-   11 phosphor-   12 polysiloxane precursor material or precursor-   13 cured polysiloxane material-   21 filler-   22 polysiloxane precursor material or precursor-   23 cured polysiloxane material-   31 housing-   32 recess-   33 carrier-   34 bonding wire and/or bonding pad-   35 radiation of the semiconductor layer sequence-   41 first carrier-   42 first connecting element-   43 second connecting element-   44 second carrier-   45 diffusive layer-   100 optoelectronic component

1-16. (canceled)
 17. A method for producing a conversion element for anoptoelectronic component comprising the steps of: A) providing a firstcarrier, selected from glass, sapphire, or patterned sapphire, B)applying a first connecting layer on the first carrier, wherein thefirst connecting layer comprises a silicone or is produced by apolysiloxane precursor material comprising the formula:

wherein T1 and T2 represent terminal groups, R1 to R4 each representside groups, 0.8≤n≤1, 0≤m<0.2 and n+m=1, and C) applying a conversionelement on the first connecting element, wherein the conversion elementis formed as a foil and comprises a phosphor mixed in a curedpolysiloxane material, which is produced by polysiloxane precursormaterial comprising the formula:

wherein T1 and T2 represent terminal groups, R1 to R4 each representside groups, 0.8≤n≤1, 0≤m<0.2 and n+m=1.
 18. The method according toclaim 17, wherein the conversion element is applied on the firstconnecting element by means of tape-casting.
 19. The method according toclaim 17, wherein the method comprises a step D): D) applying a secondconnecting layer on the conversion element, wherein the secondconnecting layer comprises a silicone or is produced by a polysiloxaneprecursor material comprising the formula:

wherein T1 and T2 represent terminal groups, R1 to R4 each representside groups, 0.8≤n≤1, 0≤m<0.2 and n+m=1.
 20. The method according toclaim 19, wherein the second connecting element is applied on a surfaceof a semiconductor layer sequence.
 21. The method according to claim 19,wherein the method comprises a step E) after step D): E) applying asecond carrier on the second connecting element, wherein the firstand/or second carrier comprise(s) sapphire, glass or a patternedsapphire substrate.
 22. An optoelectronic component comprising asemiconductor layer sequence, which is able to emit radiation, aconversion element, wherein the conversion element is arranged directlyon the surface of the semiconductor layer sequence, wherein theconversion element comprises at least two layers, a first and a secondlayer, wherein the first layer comprises a phosphor, which is mixed in acured polysiloxane material, wherein the second layer comprises afiller, which is mixed in the cured polysiloxane material, wherein thefiller is the cured and powdered polysiloxane material, wherein thecontent of total filler in the phosphor-containing first layer is equalto the volume content of the filler in the second layer, and wherein thecured polysiloxane material in the first and second layers comprises athree-dimensional crosslinking network based primarily on T-units. 23.The optoelectronic component according to claim 22, wherein the firstlayer comprises at least two different phosphors, wherein the firstphosphor is able to emit red radiation and wherein the second phosphoris able to emit green radiation.
 24. The optoelectronic componentaccording to claim 22, wherein the first layer comprises two sublayers,which are stacked one on top of the other, wherein the first sublayer isarranged directly on the surface of the semiconductor layer sequence andcomprises the phosphor emitting red radiation in operation, wherein thesecond sublayer is arranged directly on the first sublayer and comprisesa further phosphor emitting green radiation in operation.
 25. Theoptoelectronic component according to claim 22, wherein the polysiloxaneprecursor material in the first and/or second layer comprises theformula:

wherein T1 and T2 represent terminal groups, R1 to R4 each representside groups, 0.8≤n≤1, 0≤m<0.2 and n+m=1.
 26. The optoelectroniccomponent according to claim 22, wherein the polysiloxane precursormaterial is a methyl alkoxy polysiloxane having an alkoxy contentranging from 10 wt % to 50 wt %.
 27. The optoelectronic componentaccording to claim 22, wherein the first layer has a thickness of 20 μmto 80 μm.
 28. A method for producing a conversion element for anoptoelectronic component comprising the steps of: A) producing a firstlayer, for that purpose: A1) providing a polysiloxane precursormaterial, which is liquid, A2) mixing a phosphor to the polysiloxaneprecursor material, wherein the phosphor is suitable for conversion ofradiation, A3) curing the arrangement produced under step A2) to producethe first layer having a phosphor mixed in a cured polysiloxanematerial, which comprises a three-dimensional crosslinking network basedprimarily on T-units, where the ratio of T-units to all units is greaterthan 80%, B) producing a phosphor-free second layer, for that purpose:B1) providing the polysiloxane precursor material, which is liquid, B2)mixing a filler to the polysiloxane precursor material, wherein thefiller is in a cured and powdered form, wherein the filler has arefractive index, which is equal to the refractive index of the curedpolysiloxane material, B3) curing the arrangement produced under stepB2) to produce the second layer having a filler mixed in the curedpolysiloxane material, which comprises a three-dimensional crosslinkingnetwork based primarily on T-units, wherein the first and second layerare crosslinked to each other at their interface, wherein the producedconversion element is formed as a plate having a thickness of at least100 μm.
 29. The method according to claim 28, wherein the first andsecond layers are chemically crosslinked to each other at theirinterface forming a single crosslinked network.
 30. The method accordingto claim 28, wherein the polysiloxane precursor material in the firstand/or second layer comprises the formula:

wherein T1 and T2 represent terminal groups, R1 to R4 each representside groups, 0.8≤n≤1, 0≤m<0.2 and n+m=1.
 31. The method according toclaim 28, wherein the first layer is only partially cured in step A3),and the second layer is dispensed over the top of the partially curedfirst layer.
 32. The method according to claim 28, wherein the first andthe second layer comprise the same cured polysiloxane material and thethree-dimensional crosslinking network is continuous from one layer tothe other.
 33. The method according to claim 28, wherein thepolysiloxane precursor material is a methyl alkoxy polysiloxane havingan alkoxy content ranging from 10 wt % to 50 wt %.
 34. The methodaccording to claim 28, wherein the first layer has a thickness of 20 μmto 80 μm.
 35. The method according to claim 28, wherein the polysiloxaneprecursor material has a molecular weight of less than 5000 g/mol,preferably less than 1500 g/mol.
 36. The method according to claim 28,wherein the first and/or second layer(s) is/are applied by means ofspray-coating, dip-coating, spin-coating, drop-casting, tape-casting ordoctor blading.